1. Field of the Invention
The present invention relates generally to the art of manufacturing runners of the type used in blast furnace facilities for the purpose of carrying off molten slag. In a more particular sense, the invention relates to runners falling within this general category, characterized by their being of hollow construction, with means for introducing a cooling medium such as water for the purpose of cooling the molten slag to a desired temperature.
2. Description of the Prior Art
It is common practice to construct runners of a refractory material, for the purpose of forming a trough leading from a blast furnace to a car into which slag flows from the blast furnace. The molten material from the blast furnace includes, typically, both cast iron and slag. These are separated after they flow from the furnace.
Refractory material is used due to the fact that the runners wear out rapidly by reason of the abrasive effect of the molten material upon the surfaces of the runners. Indeed, in some areas of the steel industry, specially prepared refractory materials and services are employed, involving considerable expense in view of the necessity of frequent replacement thereof. Even so, the arrangements presently employed are not totally satisfactory, because the failure to cool the molten material under accurately controlled conditions results in the fact that foreign particles form in the slag and, indeed, in the pig iron as well.
The slag, although considered basically as a waste material, has many uses in other industries. For example, in the glass-making industry, the slag can be specially compounded, sized, and blended to form an important ingredient in glass making materials. This is disclosed, for example, in U.S. Pat. No. 3,822,799 to Evans, issued July 9, 1974, disclosing a method of producing a blast furnace slag product adapted for use in the manufacture of glass, by depositing successive loads of slag each having a composition within a predetermined range.
In order to produce compositions of this type, however, it is desirable that the slag be as free as possible of stones and other foreign materials forming therein if improperly cooled during the flow of the slag from the furnace to the cars used for transferring the slag to a dumping location. There thus exists at least two reasons for improving the controlled cooling of the slag as it passes within the trough or channel defined by the end-to-end runners: (a) the desirability of reducing the frequency with which runners must be replaced; and (b) minimizing the formation of "stones" and other hard foreign particles that may later resist reduction to granular sizes required in, for example, the glass-making art.
Heretofore, metal runners have been devised, including runners having tubes arranged in a tortuous path within the walls of the runners, for the purpose of circulating cooling water therethrough. However, so far as is known these have not found great popularity, perhaps because the arrangement of the tubes and tortuous passageways has not been conducive to controlled, efficient, progressive cooling of the molten slag.